Prearranged restoration procedures for such an occurrence were put into action immediately. Only two regularly operated radio circuits from White Plains to London were commercial at the time of the failure, but within two hours other radio equipments were quickly pressed into service to establish a total of 12 radio circuits to London. Full service was restored at 0540 EDT on July 24 by using the Clarenville-Penmarch West-East cable of TAT-2, which had recently been completed but was not yet in regular use, and extending the circuits to London on three carrier groups routed via Paris.
Measurements were made using the Fault Localization Test Set (FLTS) by the Oban and Clarenville cable stations and the data were reviewed. The measurements made from Oban located the fault 8 NM west of the second repeater (Repeater 50) or about 62 NM from the Scottish terminal station. A low-resistance fault was indicated.
After power was turned down on the cable, extinguishing the gas tubes, Oban turned up power and measured repeater crystal noise peaks. They were able to measure the peaks from two repeaters only, which verified the measurements made with the FLTS that the trouble was between the second and third repeaters from Oban. In the course of the repair, the actual fault was found at 61.17 NM from Oban.
Detail of TAT-1 cable route off the Scottish coast |
As the break was in shallow water, it was determined that the the cable ship Iris (owned and operated by the British Post Office) would be adequate for the repair. Fortunately the Iris was docked at her home base at Dalmuir, Scotland, and after raising steam and loading cable repeaters and test equipment, the Iris left port at 0844 EDT Saturday, July 25.
It was estimated that it would take about 16 hours for the ship to reach the location of the cable break. During the travel time of the ship further measurements were made at Clarenville and Oban to verify the initial data and make every possible refinement in their interpretation.
Since the trouble was suspected to be caused by trawler activity, arrangements were made to have two RAF planes scout the area of the measured location at daybreak; however, poor weather conditions delayed the take-off for several hours. The planes covered an area of about 150 miles radius, photographing all shipping or fishing activities they saw. The result of this survey was not conclusive.
The Iris arrived at a point about 8.6 NM west of Repeater 50 at 0023 EDT on July 26 and proceeded to grapple for the cable and pick it up. On being brought aboard the cable parted and it was necessary to make another pickup slightly to the west of the original point.
At Pickup Point 2 the cable tested clear to Clarenville and the end was buoyed off. The ship then moved to Pickup Point 3 and recovered the cable ends west and east of this point until the cable break was located. This proved to be 6.94 NM west of Repeater 50 or 61.17 NM west of Oban, in 52 fathoms of water. The cable at this point was A type.
The ship then proceeded east to Pickup Point 4, tested clear to Oban, and at 1010 EDT began to make a splice to the A cable aboard ship. This splice was completed at 1600 EDT and the cable was laid westward to the buoyed end of the cable. After reaching the buoy, the west splice was started at 1815 EDT and was completed and overboard at 2215 EDT on July 26.
Initial power was applied to the cable at 2300 EDT and action was normal. At 2345 EDT the pilots were tested through from Clarenville to Oban and other transmission tests were made. No change in the overall transmission characteristics was noted.
The cable was repaired and completely returned to service at 0135 EDT on July 27, 1959, a total elapsed time of slightly over three days.
